Stronger Glass Products

Arun Varshneya joined the University of Sheffield to obtain his B.Sc. Tech. with honors in glass technology. Following this, he secured his MS and PhD at Case Western Reserve University in Cleveland. After working at Ford Scientific Laboratories, Dearborn MI and GE Lighting Business Group in Cleveland, he joined Alfred University as a professor of glass science and engineering. As a teacher, he taught nearly all of the required glass engineering science courses both at the undergraduate and the graduate levels and much-needed business basics to all ceramic and glass engineering students. Varshneya co-founded his entrepreneurship company “Saxon Glass Technologies, Inc.” in 1996 and continues to be its CEO. The company delivers glass chemical strengthening service. Their most known product is the Ionex® chemically strengthened Type I borosilicate glass cartridge in the EpiPen autoinjector used to combat life-threatening anaphylaxis shock as a result of severe allergic reaction to beestings, peanuts, and shell foods. Arun is the solo author of the textbook, “Fundamentals of Inorganic Glasses”, now in its second edition published by the Society of Glass Technology. He is the author/co-author of nearly 150 publications, 12 patents and is the invited author of the 13-page article on “Industrial Glass” in Encyclopaedia Britannica. He is a 2018 Honorary FSGT, the 2014 Distinguished Life Member of the American Ceramic Society and recipient of the 2007 President’s Award of the International Commission on Glass. In 2011, the local media in Agra (India) cited him as one of the 25 crowning stars of Agra.

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Contrary to the usual teaching that glass products fracture only because of extrinsic factors such as an applied tensile stress, surface flaw population and environment-assisted subcritical crack growth, it is suggested that strength is additionally controlled intrinsically by the glass chemical composition. Despite the appearance of a brittle fracture, glass undergoes plastic deformations at molecular level during a stressing event. A plastic deformation occurs after a body has exceeded its elastic yield strength. In a 3-D network such as glass, there should be four network yield strengths corresponding to hydrostatic compression, hydrostatic dilation, in-plane shear and twist shear. The glass composition determines the atomic network topology which, in turn, determines these yield strengths. When the high tensile stresses during molten glass-forming exceed glass dilation yield strength, molecular cavitation occurs which acts as site for flaw nucleation. The occurrence of molecular cavitation has been established through molecular dynamic calculations. After cooling to a solid state, a glass product is susceptible to generating cracks due to handling-produced damage such as around contacts, indents and impacts. Again, it is the network yield strengths which control the generation of the complex stress fields around damage sites. One can utilize Yoffe’s analysis [Philos. Mag. A 46(4) 617-628(1982)] incorporating the superimposition of a Boussinesq stress field with a blister field to calculate these stresses, hence, selectively control radial, median, or lateral cracking around indents. Thus, the propensity to stress-assisted crack growth and ultimate fracture may be controlled by tailoring the yield strengths. A maximum in fracture strength may be found over the range of “anomalous” and “normal” silica-based glasses consistent with the experimentally-based postulation of a glass brittleness minimum as a function of density by the Asahi Glass group [Sehgal and Ito, J. Non-Cryst. Sol., 253, 126-132 (1999)]. In short, the minds of a glass scientist and a glass technologist must meet to explore new paths to manufacture stronger glass products based on glass network topological principles.